But the German club are insistent that they cannot do a deal for Dzeko if the Premier League champions are unwilling to set a realistic transfer fee.

"There should be little doubt about Dzeko being a top-class striker," Zorc told Bild.

"He is a great forward and a player one should be keen on. However, there is also still somewhat of an economic aspect.

"[A transfer] would be down to pure maths because Dzeko is under contract at Manchester City beyond the end of the season."

The Champions League quarter-finalists are on the lookout for a new striker as Polish forward Robert Lewandowski is set to leave the club in the summer after opting against signing a new contract. His current deal expires in 2014, and City's rivals United are rumoured to be interested.